"互い先" meaning in 日本語

{
  "categories": [
    {
      "kind": "other",
      "name": "日本語",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "日本語 名詞",
      "parents": [],
      "source": "w"
    }
  ],
  "forms": [
    {
      "form": "たがいせん"
    }
  ],
  "lang": "日本語",
  "lang_code": "ja",
  "pos": "noun",
  "pos_title": "名詞",
  "senses": [
    {
      "glosses": [
        "一局ごとに交代で先手になって対局すること。"
      ],
      "id": "ja-互い先-ja-noun-WoOrcPRl"
    }
  ],
  "synonyms": [
    {
      "word": "相先"
    }
  ],
  "word": "互い先"
}

{
  "categories": [
    "日本語",
    "日本語 名詞"
  ],
  "forms": [
    {
      "form": "たがいせん"
    }
  ],
  "lang": "日本語",
  "lang_code": "ja",
  "pos": "noun",
  "pos_title": "名詞",
  "senses": [
    {
      "glosses": [
        "一局ごとに交代で先手になって対局すること。"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "相先"
    }
  ],
  "word": "互い先"
}